This study is designed to determine if the menstrual cycle phase effects symptom withdrawal and caloric intake in smoking cessation. Specifically, we are trying to determine if the phase of the menstrual cycle (luteal phase vs. follicular phase) has an effect on weight gain, caloric intake, nutrient content and resting metabolic rate. We are also trying to determine if withdrawal symptoms in smoking cessation are greater in the luteal vs. follicular phase.